In the Spring of 2007 I took a course called “Paul Revere: Tough as Nails” (Materials Science course plus History of Technology course), and the final project my team and I chose was to design lesson plans for teaching non-Newtonian fluid dynamics and significance to elementary, high school, and college students. This post outlines the lesson plan ideas for an early primary school audience. To see the main project overview go here.
- Grades 1-3
- For groups of 2-3 students
- Approximately 45 minutes for the lesson
Explaining the States of Matter
Before you can continue with this lesson, your students must understand how matter takes different states.
There are four states of matter, and three you will see in everyday life. They are solid, liquid, gas and plasma. A solid has its own shape – like an ice cube. A liquid forms the shape of its container, but always has the same volume- like water. A gas fills its container completely, even if it has to change its volume – like steam. Plasma is matter so hot that it partially separates – the sun is actually made of plasma. You won’t ever see it outside of a laboratory.
Matter can change from these states by heating up or cooling down. If you put water on a stove, it boils and turns into steam. If you put it in the fridge, it freezes into an ice cube. Every substance can turn into its different states – if you heat up a rock to over 1000 degrees, it will melt into lava.
Give the students a number of objects and ask them to identify their states. (You can use a balloon filled with air for gas.) Classify the changes between states for common substances.
Main Oobleck Activity
- 130 grams of cornstarch per student (approximately 1 one-lb box per 3 students, $1.50/lb at the supermarket)
- 100 mL of water per student (tap water is fine)
- 2 cups per group
- Additional 1 cup per student
- 2 popsicle sticks per group
- One or two ‘eggs’ of Silly Putty (optional)
- Aprons for each student
Measure out the cornstarch and water for each group of students. Leave it in cups and set aside. Each group gets a cup of each and a popsicle stick to stir with.
Set aside some for yourself to mix before class begins. Add the water to the cornstarch and stir until it forms a stiff ‘batter.’ Poke it, hard – it should feel like a solid wall. Let your finger sink into it, and it should feel like a liquid. Make sure the measured proportions are correct. This material is called Oobleck- it’s a Non-Newtonian fluid, similar to silly putty. It’s nontoxic and easy to clean with water. It’s a fun tactile toy and should keep your class engaged. The lesson focuses on deciding whether or not Oobleck is a solid or a liquid. Scientifically, it’s considered a liquid – but individual students may come to their own conclusions. Fast forces leave it solid, slow forces leave it liquid. Hence, both answers are correct in this setting.
Students should have a basic understanding of the states of matter – solid, liquid and gas.
- Students learn the basics of scientific analysis – by allowing them to test, make guesses and analyze an unknown material.
- Students understand how to use their five senses and basic tools to analyze a material
- Students understand the difference between material properties (color, stickiness, and so on) and object properties (weight, size)
- Reaffirm the states of matter by exploring a “Weird” material that isn’t always solid or liquid.
- Students are comfortable making predictions of uses of material
Overview with your students the states of matter. As a class, briefly discuss what each state looks and acts like. Ask for exmaples of each. Separate students into groups of 2 or 3 and ask each to get a cup of cornstarch, cup of water and a popsicle stick. Still as a class, discuss what state of matter the cornstarch and water are. Ask them to justify their answers. If the students have trouble identifying the cornstarch as a solid (since it forms the shape of its container, for example), point out that it can be made into a pile and hold its shape. When your students agree on the states of the materials, continue on to the activity.
1) With the students in groups, instruct them to pour the water into the cornstarch and stir. Encourage them to pass it amongst their group and observe how it changes. Discuss whether it is easy or difficult to stir. Ask them to try stirring it fast and slow, and note any differences. Ask them to guess what it is – solid or liquid?
2) Introduce the substance as an unknown named “Oobleck.” Tell them to goal is to decide what state of matter it belongs to. Ask them to split it evenly amongst their group (into their individual cups.) Give them several minutes to play with the Oobleck, before asking them to return it to their container.
3) As a class, discuss experiences with the substance. Look for disagreeing accounts – was it hard, or soft? Did it flow or stay put? Did it stick together or separate? Ask students to explain the circumstances of their discoveries. Allow them to come to conclusions as a class to its behavior and nature.
4) Lead them into a more quantitative analysis. Tell the class to analyze the Oobleck with their five senses – sight, touch, hearing, taste and smell – as a group. It’s safe to eat in small quantities (though note any students with gluten allergies). For sound, tell them to stick their fingers in it and try to pull them out rapidly. It should make a wet ‘pop’. When the students are finished with their tests, reconvene as a class and compile the results on the board. Discuss their discoveries.
5) Instruct the students to test the Oobleck’s liquid/solid properties. Ask them to experiment with different rates of force – fast, medium and slow. Can they keep it as a solid in their hands? (If they’re stuck, tell them to move it rapidly like a ball, and it should stay solid.) If they let it drip, how long does it take? Can they reform pieces together? Does it stay stuck to their hands? After this analysis, reconvene as a class for the final time.
6) Ask the students again to determine whether it is a liquid or a solid. You should be able to settle on an “in-between” answer, since it can be either under different circumstances.
7) Ask the students to think of other materials that have similar properties. Potential answers include things that change phase (like ice melting into water or boiling into steam), or substances that dry (like wet paint or clay).
8) As a class, come up with possible uses for this strange material. How is it as a toy? What else could it be used for?
9) When they are done, clean up (soap and water should be enough) and replace the Oobleck in its cups.
A more extensive class could involve quantitative analysis of the Oobleck. It could be massed and have its volume measured. Students could time exactly how long it took for a single piece of Oobleck to “drip” a given distance. Quantitative analysis allows the introduction of more complex topics, such as material and object properties. Food coloring can be added – try mixing two different colors of Oobleck and noting its behavior.